TWI732093B - Microwave chemical processing reactor - Google Patents

Abstract

A processing reactor includes a microwave energy source and a field-enhancing waveguide.The field-enhancing waveguide has a field-enhancing zone between a first cross-sectional area and a second cross-sectional area of the waveguide, and also has a plasma zone and a reaction zone.The second cross-sectional area is smaller than the first cross-sectional area, is farther away from the microwave energy source than the first cross-sectional area, and extends along a reaction length of the field-enhancing waveguide.The supply gas inlet is upstream of the reaction zone.In the reaction zone, a majority of the supply gas flow is parallel to the direction of the microwave energy propagation.A supply gas is used to generate a plasma in the plasma zone to convert a process input material into separated components in the reaction zone at a pressure of at least 0.1 atmosphere.

Description

Microwave chemical treatment reactor

This application claims the priority of U.S. Patent Application No. 15/676,649 filed on August 14, 2017, which is a U.S. patent application filed on February 9, 2017 and published as U.S. Patent No. 9,767,992 Case No. 15/428,474 is a continuation; all the above applications are hereby incorporated by reference in their entirety.

The present invention relates to a microwave chemical treatment reactor.

Microwave plasma is used in the industrial chemical treatment of gases. This is usually done by coupling microwave energy to an elongated container while flowing the gas to be reacted through the container to generate plasma. Plasma breaks gas molecules into constituent substances. The microwave chemical processing system is effective because microwave plasma operates with low ion energy with relatively high power coupling efficiency and can support various gas reactions, such as the conversion of methane to hydrogen and carbon particles, and the conversion of carbon dioxide to oxygen and carbon. , And the use of other layers to coat particles and other seed materials for functionalization and composite layered materials and aggregate processing.

A typical system for chemical gas processing includes a quartz reaction chamber through which process materials flow, and a microwave magnetron source coupled to the reaction chamber via a waveguide. The input microwave energy can be continuous wave or pulsed. The system is designed to control the effective coupling of microwave energy into the reaction chamber and the gas flow in the reaction chamber to improve the energy absorption of the flowing gas. The system often includes a wedge at the intersection of the microwave guided wave and the quartz reaction chamber to concentrate the electric field in a small area, and the conductive wall of the waveguide is not exposed to the gas to be processed.

A processing reactor includes: a microwave energy source, which provides microwave energy; and a field-enhanced waveguide, which is coupled to the microwave energy source. The field enhancement waveguide has a first cross-sectional area and a second cross-sectional area. The field enhanced waveguide includes a field enhanced region located between the first cross-sectional area and the second cross-sectional area. The field enhancement waveguide also includes a plasma region and a reaction region. The second cross-sectional area is smaller than the first cross-sectional area, farther away from the microwave energy source than the first cross-sectional area, and extends along the reaction length of the reaction zone forming the field-enhanced waveguide. The microwave energy propagates in the direction along the length of the reaction. The processing reactor also includes: a supply gas inlet, through which the supply gas flows into the supply gas inlet; and a process inlet, through which the process input material flows into the process inlet and into the reaction zone. The supply gas inlet is located upstream of the reaction zone. In this reaction zone, most of the supply gas flow is parallel to the direction of microwave energy propagation. The supply gas is used to generate plasma in the plasma zone to convert the process input material into separated components in the reaction zone, wherein the conversion of the process input material occurs under a pressure of at least 0.1 atmospheres.

Reference will now be made to the embodiments of the disclosed invention, and one or more examples of these embodiments are shown in the accompanying drawings. Each example is provided in a way of explaining the technology of the present invention rather than limiting the technology of the present invention. In fact, those familiar with the art will understand that modifications and changes can be made to the technology of the present invention without departing from the scope of the technology of the present invention. For example, features shown or described as part of one embodiment can be used with another embodiment to produce a still further embodiment. Therefore, it is intended that the subject matter of the present invention covers all such modifications and changes within the scope of the attached patent application and its equivalents.

The embodiments of the system and method of the present invention are used for microwave plasma chemical processing of input materials. In some embodiments, the input material may be a gas, liquid, or colloidal dispersion. In the microwave plasma chemical processing reactor of various embodiments, the processing of the input material into separate components takes place in the reaction zone of the waveguide. In the present disclosure, one type of input material (such as gas) can be used as an exemplary material to describe the embodiments, but the embodiments are equally applicable to other types of materials, such as liquid and/or colloidal dispersions. The waveguides of the microwave chemical processing reactor of the present disclosure are field-enhanced waveguides. These field-enhanced waveguides achieve high throughput of the input material to be processed. The waveguide itself acts as a reaction chamber instead of being in contact with the microwave as in the conventional system. There are processed materials in the quartz chamber separated by the energy waveguide. The design of the reactor system provides a large volume for chemical reactions and reduces the impact of particle accumulation and the amount of particles on the walls of the reaction chamber. The accumulation of particles on the quartz wall in the conventional system reduces the efficiency of the chemical treatment because the microwave energy must penetrate the quartz wall containing the processed gas. In the system of the present invention, the microwave energy is propagated in the waveguide acting as the reaction chamber for the processed material, and therefore the microwave energy will not be affected by particles that may be deposited on the walls of the chamber (ie, the waveguide) Hinder.

As used herein, the term "field-enhanced waveguide (FEWG)" refers to a waveguide having a first cross-sectional area and a second cross-sectional area, wherein the second cross-sectional area is smaller than the first cross-sectional area and larger than the first cross-sectional area. Keep away from microwave energy. The reduction in cross-sectional area enhances the field by concentrating the microwave energy, and the size of the waveguide is set to maintain the propagation of the specific microwave frequency used. The second cross-sectional area of the FEWG extends along the reaction length of the reaction zone forming the FEWG. There is a field enhancement zone between the first cross-sectional area and the second cross-sectional area of the FEWG. In some embodiments, the field enhancement zone may change the cross-sectional area in a continuous manner (e.g., linearly or non-linearly) or abruptly (e.g., via one or more discrete steps). In some embodiments, the pressure in the FEWG is 0.1 atm to 10 atm, or 0.5 atm to 10 atm, or 0.9 atm to 10 atm, or greater than 0.1 atm, or greater than 0.5 atm, or greater than 0.9 atm.

In some embodiments, the microwave plasma chemical processing reactor of the present disclosure has one or more supply gas inlets into which the supply gas flows and one or more process inlets into which the input material flows. The supply gas inlet and the process inlet are located in or upstream of the reaction zone, and the supply gas is used to generate plasma in the reaction zone. In some embodiments, the supply gas flow rate is 1 slm (standard liter per minute) to 1000 slm, or 2 slm to 1000 slm, or 5 slm to 1000 slm, or greater than 1 slm, or greater than 2 slm, or greater than 5 slm . In some embodiments, the process material is a gas, and the flow rate is 1 slm (standard liter/minute) to 1000 slm, or 2 slm to 1000 slm, or 5 slm to 1000 slm, or greater than 1 slm, or greater than 2 slm , Or greater than 5 slm. In some embodiments, the process material is a liquid or colloidal dispersion, and the flow rate is less than 1% to more than 100% of the supply gas flow rate.

In some embodiments, the microwave plasma chemical processing reactor of the present disclosure has a single microwave energy generator, which is a microwave energy source coupled to one or more FEWGs. In some embodiments, the microwave plasma chemical processing reactor of the present disclosure has more than one microwave energy generator coupled to more than one FEWG. In some embodiments, the microwave energy is continuous wave or pulsed. In some embodiments, the power of the microwave energy generator is 1 kW to 100 kW.

In some embodiments, the microwave plasma chemical treatment reactor of the present disclosure has more than one reaction zone, the more than one reaction zone is connected together and has one or more outlets, and the separated components are derived from the one or More than one outlet collection.

In some embodiments, the microwave plasma chemical processing reactor of the present disclosure contains a plurality of FEWGs with different geometric structures, and the different geometric structures include a manifold configuration and a mesh configuration. This article will describe these geometric structures more fully.

In some embodiments, the microwave plasma chemical processing reactor of the present disclosure has a reaction zone with walls, and the supply gas inlet and the process inlet supply gas (used to generate microwave plasma) and input materials through the walls. Provided to the reaction zone. In some embodiments, there are a plurality of supply gas inlets and process inlets, and the plurality of supply gas inlets and process inlets provide the supply gas and input materials to the reaction zone with a controlled mass fraction through the walls. Providing the supply gas and input material to the reaction zone with controlled mass fractions through the walls can reduce the deposition of separated components on the reaction zone walls.

Some embodiments involve microwave plasma chemical treatment of hydrocarbon gases using various techniques, including pulsing microwave energy to control the plasma energy. The ability to control the energy of the plasma enables the selection of one or more reaction paths in the conversion of hydrocarbon gas to specific separated components. Pulsed microwave energy can be used to control the energy of the plasma, because the short-lived high-energy matter generated when the plasma is ignited can be regenerated at the beginning of each new pulse. The plasma energy is controlled to have a lower average ion energy than the conventional technology, but at a high enough level to enable the target chemical reaction to occur under high gas flow and high pressure.

Microwave plasma chemical processing systems using pulsed microwave energy have been developed. These microwave plasma chemical processing systems control the plasma energy and have extremely high cracking efficiency exceeding 90%. However, these conventional systems use a low flow rate of less than 1 standard liter per minute (slm) and a small gas volume in the plasma, resulting in a low production rate and high production cost. These conventional systems cannot increase the gas flow rate and the gas volume in the plasma while using high frequency microwave pulses (for example, higher than approximately 100 Hz), because the plasma cannot be fast enough when using large volume and high flow gas. To keep up with the pulse. Microwave chemical processing system

In the present disclosure, microwave plasma can be generated in the supply of gas and/or process materials, and the energy in the plasma is sufficient to form separate components of the process material molecules. In some embodiments, the microwave energy source is coupled to the FEWG, the plasma is generated along the plasma region of the FEWG, and the process materials are separated into components by the plasma along the reaction length in the FEWG. In some embodiments, the microwave energy is directly coupled into the plasma and is not coupled into the plasma through a dielectric wall as in conventional methods.

Figure 1A shows a conventional microwave chemical processing system. As shown in FIG. 1A, the microwave chemical processing system 100 generally includes a reaction chamber 101; one or more gas inlets 102 configured to receive processing materials 108 flowing into the reaction chamber; one or more outlets 103, which is configured to collect the separated products leaving the reaction chamber 101; and the microwave energy source 104, which is coupled to the reaction chamber via the waveguide 105; and other elements not shown for simplicity. The microwave energy 109 generates microwave plasma 106 in the reaction chamber 101 and provides energy for reaction. The microwave transmitter circuit 107 can control the microwave energy 109 emitted from the microwave energy source 104 to be continuous wave or pulsed. Given appropriate conditions, the energy in the plasma will be sufficient to process the material molecules to form separate components. Microwave chemical processing reactor with field enhanced waveguide (FEWG)

The FEWG of this disclosure effectively transmits microwave frequency electromagnetic energy. The FEWG of the present disclosure is made of conductive material and the cross-section can be rectangular, circular or elliptical. As shown in Figure 1B, the widest dimension of the waveguide is called the "a" dimension and determines the range of operating frequency. The narrowest dimension determines the power handling capability of the waveguide and is called the "b" dimension. Figure 1C shows an example of the field enhancement region of FEWG, where the widest dimension "a" is kept constant to effectively transmit the selected microwave energy frequency, and the narrower dimension "b" is reduced along the length of the FEWG to concentrate the microwave energy density. Figure 1C depicts the linear reduction of the size "b"; however, the reduction of the size "b" can be non-linear (such as parabolic, hyperbolic, etc.), with different reduction rates along the length (such as linear reduction) Different slopes, linear slopes in one section and non-linear slopes in another section), or contain sudden steps to reduce the length of the dimension "b".

The embodiments described herein are applicable to both fixed wave systems (where the peak value is kept at the same position) and traveling wave systems (where the peak value can be moved).

Figures 2 and 3 show an embodiment of the microwave chemical processing system of the present disclosure, in which the FEWG is coupled to a microwave energy generator (ie, a microwave energy source), and plasma is generated from the gas supply in the plasma region of the FEWG, And the reaction length of FEWG serves as a reaction zone to separate the process materials into individual components. The reactor of the present invention as demonstrated in FIGS. 2 and 3 does not have a dielectric barrier between the field enhancement zone and the reaction zone of the field enhancement waveguide. In contrast, the reaction zone of the conventional system is enclosed in a dielectric barrier (such as the quartz chamber described earlier). The propagation direction of the microwave energy is parallel to most of the supply gas flow and/or the process material flow, and the microwave energy enters the waveguide upstream of the part of the FEWG where the separated components are generated.

As shown in FIG. 2, the microwave chemical processing reactor 200 according to some embodiments generally includes FEWG 205; one or more inlets 202, which are configured to receive supply gas and/or process materials flowing into FEWG 205 208a; microwave energy source 204, which is coupled to FEWG 205; and other components not shown for simplicity.

In some embodiments, the microwave circuit 207 controls the pulse frequency at which the microwave energy 209 from the microwave energy source 204 is pulsed. In some embodiments, the microwave energy 209 from the microwave energy source 204 is a continuous wave.

FEWG 205 has a length L. Portion of the system FEWG 205 has a length L _A (shown in FIG. 2 and FIG. 3) as to have a length of more FEWG L _B (2 and 3 shown in FIG. FIG.) Closer to the microwave energy generator. Throughout this disclosure, various portions of FEWG represented by capital letters below a portion plus L FEWG the standard described _{(e.g., L A, L 0, L} B, L 1, L 2), and synonymously, the FEWG also different portions of the length by adding capital letter L represents the length of a portion under the standard of FEWG described _{(e.g., L A, L 0, L} B, L 1, L 2).

The cross-sectional area of FEWG in length L _B is smaller than the cross-sectional area of FEWG in length L _A. The length L ₀ FEWG FEWG positioned between the length L _A and L _B, and having a decreasing cross-sectional area along the propagation path of the microwave energy. In some embodiments, the cross-sectional area of the FEWG along the length L _{0 decreases in a continuous manner.} In some embodiments, L ₀ FEWG the cross-sectional area decreases linearly along the length between the length L _A and L _B. In some embodiments, L ₀ of the cross-sectional area along the length FEWG nonlinearly decreases between L _A and L _B, such as parabolically, hyperbolically, or exponentially decreases logarithmically. In some embodiments, L ₀ in the cross-sectional area along the length FEWG reduce abrupt manner between the length L _A and L _B, such as reducing discrete steps via one or more. The reduction in cross-sectional area is used to concentrate the electric field, thereby increasing the microwave energy density, while still providing a larger amount of area in which plasma can be formed compared to conventional systems. When using microwave energy of 2.45 GHz frequency, FEWG the portion having a length L _B (shown in FIG. 2 and FIG. 3) may have a dimension of 0.75 inches by 3.4 inches of rectangular cross-section. This cross-sectional area is much larger than the conventional system whose plasma generation area is usually less than one square inch. The dimensions of the different parts of FEWG 205 are set according to the microwave frequency in order to properly play the role of the waveguide. For example, for an elliptical waveguide, the cross-sectional size can be 5.02 inches by 2.83 inches for 2.1 GHz-2.7 GHz.

In conventional gas processing systems, the limited area in which plasma can be formed (such as less than one square inch as described above) limits the volume in which gas reaction can occur. In addition, in conventional systems, microwave energy enters the reaction chamber through a window (usually quartz). In these systems, a dielectric material (e.g., particulate carbon) is coated on the window during processing, resulting in a decrease in power delivery over time. If these separated components absorb microwave energy, this can be very problematic because the separated components prevent microwave energy from coupling into the reaction chamber to generate plasma. Therefore, rapid accumulation of by-products (such as carbon particles produced by the gas reaction) can occur and limit the operating time of the processing equipment. In an embodiment of the present invention, the system 200 and other embodiments described below are designed to not use windows in the reaction zone; that is, use a parallel propagation/gas flow system in which energy enters upstream of the reaction. Thus, more energy and power can be coupled into the plasma from the microwave energy source. The lack of the window and the larger volume of the waveguide 205 compared with the limited reaction chamber volume in the conventional system greatly reduces the particle accumulation problem caused by the limited running time, thereby improving the production efficiency of the microwave processing system.

The microwave energy 209 in FIG. 2 generates microwave plasma 206 in the supply gas and/or the process material in the plasma region _{of the length L 1} (shown in FIG. 2 and FIG. 3) having the length of the FEWG 205. Plasma zone has a length L ₁ located on the inner portion FEWG L _B, as compared to the length L _A, the cross sectional area of the microwave energy smaller and higher density of the portion _B L. In some embodiments, a supply gas different from the process material is used to generate the microwave plasma 206. The supply gas may be, for example, hydrogen, helium, an inert gas such as argon, or a mixture of more than one type of gas. In other embodiments, the supply gas is the same as the process material, where the process material is the material from which the separated components are generated.

In some embodiments, the supply of gas and / or process material inlet 202 is located in L upstream part _B FEWG of, or within part FEWG of L _0, or in the inner portion FEWG of L _A, or is located in L _A upstream portion FEWG of. In some embodiments, the portion L _{1 of} the FEWG extends from a position along the FEWG downstream of the position where the supply gas and/or process material 208a enters the FEWG to the end of the FEWG or to the inlet of the supply gas and/or process material and the FEWG The position between the ends of 205. In some embodiments, the portion L _{1 of the} FEWG extends from the point where the supply gas and/or process material 208a enters the FEWG to the end of the FEWG or extends to a position between the inlet of the supply gas and/or process material and the end of the FEWG .

The generated plasma 206 provides energy for the reaction in the process material 208b in the reaction zone 201 of the FEWG 205, the reaction zone 201 having a reaction length L ₂ . In some embodiments, the reaction zone L _{2 where the} process material 208a enters the FEWG 205 extends to the end of the FEWG 205 or extends to a position between the inlet of the process material and the end of the FEWG 205. Given appropriate conditions, the energy in the plasma 206 will be sufficient to process the material molecules to form separate components. One or more outlets 203 are configured to collect the separated products leaving the FEWG 205 downstream of the reaction zone portion 201 of the FEWG where the reaction occurs in the process material 208b. In the example shown in FIG. 2, the propagation direction of the microwave energy 209 is parallel to most of the supply gas and/or process material flow 208 b, and the microwave energy 209 enters the FEWG 205 upstream of the reaction zone 201 where the separated components of the FEWG are generated.

In some embodiments, the pressure barrier 210 through which microwave energy can penetrate may be located in the microwave energy source 204, near the outlet of the microwave energy source, or located between the microwave energy source 204 and the plasma 206 generated in the FEWG. At other locations. The pressure barrier 210 can serve as a safety measure to prevent the plasma from possibly flowing back into the microwave energy source 204. Plasma does not form at the pressure barrier itself; in fact, the pressure barrier is only a mechanical barrier. Some examples of materials that can be made into pressure barriers are quartz, ethylene tetrafluoroethylene (ETFE), other plastics, or ceramics. In some embodiments, there may be two pressure barriers 210 and 211, of which one or two pressure barriers 210 and 211 are located in the microwave energy source 204, located near the outlet of the microwave energy source, or located between the microwave energy source 204 and the FEWG At other locations between the plasma 206 generated in the In some embodiments, the pressure barrier 211 is closer to the plasma 206 in the FEWG than the pressure barrier 210, and there is a pressure jet 212 between the pressure barrier 210 and 211 to prevent the pressure barrier 211 from failing.

In some embodiments, a plasma barrier (not shown) is included in the system to prevent the plasma from propagating to the microwave energy source 204 or supply gas and/or process material inlet 202. In some embodiments, the plasma barrier is a ceramic or metal filter with holes to allow microwave energy to pass through the plasma barrier, but prevent most of the plasma material from passing through. In some embodiments, most of the plasma material will not pass through the plasma barrier because the hole will have a high aspect ratio, and the plasma material will recombine when it hits the sidewall of the hole. In some embodiments, the plasma barrier is located between part L ₀ and L ₁ , or located _{upstream of part L 1} and at the inlet 202 (in embodiments where the inlet 202 is within the part L ₀ ) and the microwave energy source 204 is in the downstream part L ₀ .

FIG. 3 shows another embodiment of the microwave chemical processing system 300, in which the supply gas and the processing materials are injected at different locations. According to some embodiments, the microwave chemical processing system 300 generally includes a FEWG 305; one or more supply gas inlets 302 configured to receive the supply gas 308a flowing into the FEWG 305; one or more process material inlets 310, It is configured to receive the process material 311a; and the microwave energy source 304, which is coupled to the FEWG 305; and other components not shown for simplicity. The position of the process material inlet 310 is downstream of the position of the supply gas inlet 302, wherein the downstream is defined in the direction of microwave energy propagation.

In some embodiments, the microwave circuit 307 controls the pulse frequency at which the microwave energy 309 from the microwave energy source 304 is pulsed. In some embodiments, the microwave energy from the microwave energy source 304 is a continuous wave.

The illustrated embodiment similar to FIG. 2, in the FIG. 3 FEWG 305 has a portion _{L A, L 0, L B} , L 1, and L _2, where L _B having a cross section smaller than the cross-sectional area of the L _A area, having a portion between the portion L ₀ and L _B L _a decreasing cross-sectional area, L ₁ based plasma generating portion, and the line L ₂ as part of the reaction zone.

309 L of microwave energy within _a microwave plasma 306 is generated in the gas supply 308b in the length L FEWG 305 of the plasma region. In some embodiments, the portion L ₁ extends from a position along the FEWG 305 downstream of the position where the supply gas 308 a enters the FEWG 305 to the end of the FEWG 305 or to a position between the inlet of the supply gas and the end of the FEWG 305. In some embodiments, the portion L ₁ extends from where the supply gas 308 a enters the FEWG 305 to the end of the FEWG 305 or to a position between the inlet of the supply gas and the end of the FEWG 305. One or more additional process material inlets 310 are configured to receive process material flowing into the FEWG at a second set of locations downstream of the supply gas inlet 302. The generated plasma 306 provides energy for reaction in the reaction zone 301 of the FEWG 305, the reaction zone 301 having a reaction length L ₂ . In some embodiments, part of the L ₂ process material 311a enters the FEWG 305 and extends to the end of the FEWG 305 or extends to a position between the inlet of the process material and the end of the FEWG 305. Given appropriate conditions, the energy in the plasma will be sufficient to process the material molecules to form separate components. One or more outlets 303 are configured to collect the separated products leaving the FEWG 305 downstream of the portion 301 where the reaction occurs. In the exemplary system 300 shown in FIG. 3, the propagation direction of the microwave energy 309 is parallel to most of the supply gas flow 308b and the process material flow 311b, and the microwave energy 309 enters upstream of the reaction part 301 of the FEWG that produces separated components. FEWG 305.

In some embodiments, one or more pressure barriers through which microwave energy can penetrate may be located in the microwave energy source 304, near the outlet of the microwave energy source, or located in the plasma 306 generated in the microwave energy source 304 and the FEWG. At other locations in between (similar to the situation described above and depicted in Figure 2). In some embodiments, there are two pressure barriers and a pressure jet located between the pressure barriers to prevent failure of the barrier closer to the plasma 306 in the FEWG.

In some embodiments, _{the wall of the reaction zone L 2} is configured such that the supply gas inlet and the process material inlet provide the supply gas and the process material to the reaction zone through the wall of the FEWG. For example, the walls may have a series of holes serving as secondary supply gas inlets, the supply gas and/or process materials may be inserted into the FEWG through the secondary supply gas inlets, or the walls may be supply materials and/or The process material is permeable, or the walls can be porous. Supplying supply gas and input material to the reaction zone through the walls can reduce the deposition of separated components on the reaction zone wall by forming a reactive plasma close to the wall that etches away the deposited material.

In some embodiments, there are a plurality of supply gas inlets and process inlets, and the plurality of supply gas inlets and process inlets provide the supply gas and input materials to the reaction zone L ₂ through the wall of the FEWG. In some embodiments, there are a plurality of supply gas inlets and process inlets, and the plurality of supply gas inlets and process inlets are configured to provide a controlled mass fraction of supply gas and input materials to the reaction zone L through the FEWG wall. ₂ . Introducing the supply gas and process materials into the FEWG at a controlled mass fraction can more effectively etch away any materials deposited on the walls of the FEWG in the reaction zone. As described above, FEWG (e.g., in the FIG. 3 and FIG 2205 of 305) has a total length L; portion of the total length L _A and L _B portion, wherein the cross-sectional area is less than L _B L _A of area; section L _1, plasma is generated along the portion of L _1; and a portion of the total length L _2, L ₂ is converted into the portion of separated components along the process material. In some embodiments, the total length L of the waveguide is 1 cm to 1000 cm. In some embodiments, the length L ₀ of the waveguide is 1 cm to 100 cm. In some embodiments, the length L ₁ of the waveguide is 1 cm to 100 cm. In some embodiments, the length L ₂ of the waveguide is 1 cm to 1000 cm. In some embodiments, the total length L of the waveguide is 30 cm to 60 cm. In some embodiments, the length L ₀ of the waveguide is 10 cm to 40 cm. In some embodiments, the length L ₁ of the waveguide is 10 cm to 30 cm. In some embodiments, the length L ₂ of the waveguide is 5 cm to 20 cm. In some embodiments, the length L _A portion FEWG for a microwave frequency of 2.45 GHz based e.g. 0-10 inches, but this length may vary depending upon the use of microwave frequencies. In some embodiments, portions FEWG length L _B based e.g. 10-20 inches, this will depend upon such factors as the gas flow velocity and the microwave power. For example, a higher gas flow velocity will increase the length of the reaction zone. In some embodiments, the length L ₁ is greater than 10%, or greater than 20%, or greater than 30%, or greater than 40%, or greater than 50%, or greater than 60%, or greater than 70%, or greater than 80% of the waveguide length L , Or 10% to 90%, or 20% to 80%, or 30% to 70%. In some embodiments, the length L ₂ is greater than 5%, or greater than 10%, or greater than 15% or greater than 20%, or greater than 25% or greater than 30%, or greater than 35%, or greater than 40% of the waveguide length L , Or greater than 45%, or greater than 50%, or greater than 55%, or greater than 60%, or 1% to 90%, or 1% to 70%, or 1% to 50%, or 10% to 50%, or 10% to 40%, or 20% to 40%.

In some embodiments, the FEWG (eg, 205 in FIG. 2 and 305 in FIG. 3) is configured to maintain a pressure of 0.1 atm to 10 atm, or 0.5 atm to 10 atm, or 0.9 atm to 10 atm, or Greater than 0.1 atm, or greater than 0.5 atm, or greater than 0.9 atm. In many conventional systems, microwave chemical processing is operated under vacuum. However, in the embodiment of the present invention where the plasma is generated in the FEWG, operating in a positive pressure environment helps prevent the generated plasma from being fed back to the microwave energy source (for example, 204 in FIG. 2 and in FIG. 3 Of 304).

Size FEWG (e.g., 205 of FIG. 2 and FIG. 3 of 305) may have a length L _B is within 0.75 inches by 3.4 inches of rectangular cross-section, corresponding to the frequency of 2.45 GHz of microwave energy. Other possible dimensions L _B of the system for other microwave frequencies, and depends on the state of waveguide mode, such as the cross-sectional dimension may be 3-6 inches. Size FEWG (e.g., 205 of FIG. 2 and FIG. 3 of 305) may have a length L _A in, for example, 1.7 inches by 3.4 inches of rectangular cross-section, corresponding to the frequency of 2.45 GHz of microwave energy. Other dimensions of L _A system for other microwave frequencies possible. FEWG can be made of any innate conductive material or material with sufficient conductive coating to spread more than 90% of the incoming power. Some examples of FEWG materials are metallic materials, metallic materials with conductive coatings, ceramic materials, ceramic materials with conductive coatings, stainless steel, stainless steel coated with conductive layers (for example, Al, Ni, Au or Ni/Au alloy) , Stainless steel with aluminum lining, or ceramic material coated with conductive layer. It should be noted that the FEWG acts as a chamber in which plasma is generated and the process material reaction occurs, rather than having a separate waveguide and quartz reaction chamber as in the conventional system. Having the FEWG act as a reactor chamber provides a much larger volume (e.g., up to 1000 L) in which gas reactions can occur. This achieves a high flow rate of the process material to be processed without being restricted by the accumulation of carbon particles as occurs in conventional systems. For example, the flow rate of the process material entering the waveguide (for example, 205 in FIG. 2 and 305 in FIG. 3) through the inlet (for example, 202 in FIG. 2 and 310 in FIG. 3) can be 1 slm (standard liters per minute) ) To 1000 slm, or 2 slm to 1000 slm, or 5 slm to 1000 slm, or greater than 1 slm, or greater than 2 slm, or greater than 5 slm. The flow rate of the supply gas entering the waveguide (for example, 205 in FIG. 2 and 305 in FIG. 3) through the inlet (for example, 202 in FIG. 2 and 302 in FIG. 3) can be, for example, 1 slm to 1000 slm, or 2 slm to 1000 slm, or 5 slm to 1000 slm, or greater than 1 slm, or greater than 2 slm, or greater than 5 slm. Depending on the gas plasma properties (for example, secondary electron emission coefficient) that produce sufficient plasma density, the flow rate can be 1 slm to 1000 slm and the pressure can be up to 14 atm.

In some embodiments, the process material is provided to the liquid in the FEWG via the process material inlet. Some examples of liquids that can be used as process materials are water, alkanes, alkenes, alkynes, aromatic hydrocarbons, saturated and unsaturated hydrocarbons (for example, saturated and unsaturated hydrocarbons of alkanes, alkenes, alkynes, or aromatic hydrocarbons) , Ethanol, methanol, isopropyl alcohol (ie, isopropanol), or a mixture thereof (for example, a 50/50 mixture of ethanol/methanol). In some embodiments, the liquid process materials listed above will produce carbon and hydrogen separation components. In some embodiments, the flow rate of the liquid may be a percentage of the supply gas flow entering the reactor, such as 0.001% to 1000%, or 0.001% to 100%, or 0.001% to 10%, or 0.001% to 1%, Or 0.001% to 0.1%, or 0.01% to 1000%, or 0.01% to 100%, or 0.01% to 10%, or 0.01% to 1%, or 0.01% to 0.1%.

In some embodiments, the process material is provided to the colloidal dispersion (ie, a mixture of solid particles suspended in a liquid or gas) in the FEWG through the process material inlet. For example, the colloidal dispersion may include carbon particles. Some examples of colloidal dispersions that can be used as process materials are solid particles from Group 16, Group 14, Group 10, Group 9, Group 5, Group 2, and Group 1 mixed with liquid or gas , Its alloys and their mixtures. In some embodiments, the solid particles listed above can be mixed with liquids such as water, alkanes, alkenes, alkynes, aromatic hydrocarbons, saturated and unsaturated hydrocarbons (e.g., alkanes, alkenes, alkynes, or Saturated and unsaturated hydrocarbons of aromatic hydrocarbons), ethanol, methanol, isopropyl alcohol, or mixtures thereof (for example, a 50/50 mixture of ethanol/methanol). Examples of gases are Group 1 and Groups 15-18, and inorganic compounds (for example, Group 14 hydrides). Some examples of separation components that can be produced from the colloidal dispersion process materials listed above are solid inorganic materials coated in organic materials (for example, silicon coated with graphene), and composite materials with interlayers of organic/inorganic materials (For example, a silicon core with a carbon layer encapsulating the silicon, which is coated with an additional inorganic layer). In some embodiments, the flow rate of the colloidal dispersion may be a percentage of the supply gas flow entering the reactor, such as 0.001% to 1000%, or 0.001% to 100%, or 0.001% to 10%, or 0.001% to 1. %, or 0.001% to 0.1%, or 0.01% to 1000%, or 0.01% to 100%, or 0.01% to 10%, or 0.01% to 1%, or 0.01% to 0.1%.

In some embodiments, the process material is a gas. In some embodiments, the process material is a hydrocarbon gas, such as C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ . In some embodiments, the process material is methane, and the separated components are hydrogen and nanoparticulate carbon. In some embodiments, the process material is carbon dioxide with water, and the separated components are oxygen, carbon, and water. In some embodiments, the process material is H ₂ S, and the separated components are hydrogen and sulfur. In some embodiments, the process material does not contain carbon dioxide. In some embodiments, the process materials are materials based on complex gases, such as SiH ₄ , trimethylaluminum (TMA), trimethylgallium (TMG), glycidyl methacrylate (GMA), SF ₆ , Or other materials used in the deposition and etching of metals and dielectrics in the semiconductor industry.

In some embodiments, one of the separated components is nanoparticulate carbon, such as but not limited to carbon black, carbon nano-onion (CNO), neck-shaped CNO, carbon nanosphere, graphite, pyrolytic graphite, graphite Olefins, graphene nanoparticles, graphene flakes, fullerenes, mixed fullerenes, single-walled nanotubes and multi-walled nanotubes. One or more of these nanoparticulate carbons can be produced during the operation of a specific process. In some embodiments, the separation component comprises nanoparticulate carbon in the viscose polymer-the nanoparticulate carbon can also be described as aggregate particles. In some cases, the viscose or aggregate particles contain many nanoparticulate carbon particles. In some embodiments, the viscose or aggregate particles comprise nanoparticulate carbon particles and have a size greater than 50 microns, or greater than 100 microns, or greater than 200 microns, or greater than 300 microns, or greater than 500 microns, or greater than 1000 microns, Or 1 micron to 1000 micrometers, or 10 micrometers to 1000 micrometers, or 100 micrometers to 1000 micrometers, or 100 micrometers to 500 micrometers. Tuning microwave energy in a microwave chemical processing system

Different process materials require different amounts of energy to react into different separated components. In the present disclosure, the available reaction path can be selected by changing the average energy of the plasma. In some embodiments, the microwave energy coupled to the plasma is pulsed, and the average energy of the plasma is selected by controlling the duration and frequency of the microwave energy pulse, the duty cycle, the shape, and the time average output power level, and therefore Choose the reaction path. Additional details of tuning microwave energy in a microwave chemical processing system are disclosed in US Patent Application No. 15/351,858 entitled "Microwave Chemical Processing" and filed on November 15, 2016, which is the present application It is owned by the assignee of the case and is hereby incorporated by reference in its entirety.

In some embodiments, the average energy in the plasma is controlled by changing the pulse period and selecting the pulse frequency to achieve the desired plasma energy. In addition, in some embodiments, the average energy of the plasma is controlled by controlling the duty cycle. This can be understood by considering the situation where both the time average input power and the pulse period remain constant and the duty cycle varies. A shorter duty cycle will increase the amount of power coupled into the chamber when the microwave energy is turned on. This is advantageous because a relatively low amount of power (ie, time average power) can be used to generate reaction products from reaction paths that cannot be facilitated by continuous waves at the same power.

In some embodiments, the reaction path can be selected by controlling the time average power input to the plasma. For example, if the duty cycle and pulse frequency remain constant, and the power input to the microwave generator is increased, the energy of the plasma will increase. As another example, if the duty cycle and pulse frequency remain constant, and the power is more efficiently coupled into the reaction chamber, the energy of the plasma will increase.

In some embodiments, the reaction path can be selected by controlling the shape of the microwave energy pulse. In some embodiments, the microwave pulse is a rectangular wave, where the power is constant during the duration of the pulse period when the microwave is turned on. In some embodiments, the pulse power is not constant during the duration of the pulse period when the microwave power is turned on. In some embodiments, the microwave pulses are triangular waves, or trapezoidal waves, or different wave patterns. During the time period when energetic species are present in higher fractions (that is, at the beginning of the pulse, before the plasma reaches equilibrium), the plasma may be referred to as diffusive. In some embodiments, the microwave energy is increased during the time period when the plasma is diffusive, thereby increasing the time average fraction of high-energy substances in the plasma.

As described above, tuning the pulse frequency, duty cycle, and pulse shape can enable the generation of higher fractions of higher energy materials in the plasma to obtain a given time average input power. Higher energy substances can realize additional reaction paths that are not advantageous in terms of energy in other situations.

_{The above technology can be further understood by using methane (CH 4} ) to be separated into hydrogen and nanoparticulate carbon as an exemplary process material. Generally, 4-6 eV is required to dissociate methane (CH ₄ ); however, plasma energy usually stays at approximately 1.5 eV after the initial ignition energy spike. By pulsing microwaves, the average plasma energy (ie, time average plasma energy) is maintained at a higher level, where the frequency and duration of the pulse control the average plasma energy. Specifically, pulse parameters such as frequency and duty cycle can be controlled to provide an average plasma energy of 4-6 eV to select a specific dissociation reaction of methane. Another advantage of pulsing microwave energy is that the energy is more distributed throughout the chamber into which the microwaves are being input. In the conventional system, in an equilibrium state, the plasma forms a dense layer of ionized material in the chamber toward the position of microwave input. The dense layer of ionized material absorbs the incoming microwave energy and thus prevents further microwave energy from passing through. Penetrate deeper into the chamber. The high-frequency pulses of the present disclosure maintain the plasma in an unbalanced state for a larger time fraction, and the dense ionized material layer exists for a smaller time fraction, thereby allowing microwave energy to penetrate deeper into the chamber and the plasma is in Produced in a larger volume in the chamber.

More generally, in various embodiments of the present disclosure, the average energy of the plasma during the entire duration of the pulse period may be 0.9 eV to 20 eV, or 0.9 eV to 10 eV, or 1.5 eV to 20 eV, Or 1.5 eV to 10 eV, or greater than 0.9 eV, or greater than 1.5 eV. The specific value to which the plasma energy is tuned will depend on the type of process material used.

In the microwave processing system described above, the microwave energy source is controlled by a microwave transmitter circuit (for example, 207 in FIG. 2 and 307 in FIG. 3), which can convert the microwave energy emitted from the source The control is continuous wave or pulse type. In some embodiments, the microwave transmitter circuit uses a magnetron to generate microwave energy at, for example, 915 MHz, 2.45 GHz, or 5.8 GHz. In order to control the output power of microwave energy, the microwave transmitter circuit can pulse the magnetron under various frequencies and working cycles. Each microwave transmitter circuit is designed for a specific range of pulse frequency, duty cycle, shape, and output power level. The selection of specific values of these parameters is used to tune the chemical reaction path in the process material.

In some embodiments, the microwave control circuit implements 500 Hz to 1000 kHz, or 1 kHz to 1000 kHz, or 10 kHz to 1000 kHz, or 40 kHz to 80 kHz, or 60 kHz to 70 kHz, or greater than 10 kHz, or Pulse frequency greater than 50 kHz, or greater than 100 kHz. In some embodiments, the microwave source emission has a range of 1 kW to 100 kW, or 1 kW to 500 kW, or 1 kW to 1 MW, or 10 kW to 5 MW, or greater than 10 kW, or greater than 100 kW, or greater than 500 Continuous wave or pulsed microwave energy of kW, or greater than 1 MW, or time average power greater than 2 MW. The pulse period has a first duration in which the microwave power is on, and a second duration in which the microwave energy is off or at a lower power than the first duration. In some embodiments, the second duration is longer than the first duration. The optimal duty cycle for a given system depends on many factors, including microwave power, pulse frequency, and pulse shape. In some embodiments, the duty cycle (ie, the fraction of the pulse period in which the microwave energy is turned on, expressed as a percentage) is 1% to 99%, or 1% to 95%, or 10% to 95%, or 20% To 80%, or 50% to 95%, or 1% to 50%, or 1% to 40%, or 1% to 30%, or 1% to 20%, or 1% to 10%, or less than 99% , Or less than 95%, or less than 80%, or less than 60%, or less than 50%, or less than 40%, or less than 30%, or less than 20%, or less than 10%. Microwave chemical treatment reactor with multiple field-enhanced waveguides

4A to 4D show block diagrams showing an embodiment of the microwave chemical processing system of the present disclosure, in which multiple FEWGs are coupled to one or more microwave energy generators (ie, microwave energy sources). The FEWG in these embodiments can share some or all of the features of the system described above. The supply gas and process material input in these embodiments can also share some or all of the features described above. In some embodiments, each FEWG has a reaction zone. In some embodiments, plasma is generated from the supply gas in the plasma zone in each of the FEWGs, and the reaction length of each of the FEWGs serves as a reaction zone to separate the process materials into individual Components. In some embodiments, the reaction zones are connected together and the microwave chemical processing system has an outlet for separating components. In some embodiments, the reaction zones are connected together and the microwave chemical processing system has more than one outlet for separating components. In some embodiments, each reaction zone has its own outlet for separating components.

Figure 4A shows an embodiment in which there is one microwave energy generator 401 coupled to multiple FEWGs 402, and the reaction zones of the FEWGs are all connected together so that there is a single outlet 403 for collecting separated components.

Figure 4B shows an embodiment where there is one microwave energy generator 401 coupled to multiple FEWGs 402, and the reaction zones of some FEWGs are connected together so that there is more than one outlet 403 for collecting separated components.

Figure 4C shows an embodiment where there is more than one microwave energy generator 401 coupled to multiple FEWG 402, and the reaction zones of the FEWG are all connected together so that there is a single outlet 403 for collecting the separated components.

Figure 4D shows an embodiment where there is more than one microwave energy generator 401 coupled to multiple FEWGs 402, and the reaction zones of some FEWGs are connected together so that there is more than one outlet 403 for collecting separated components.

Figures 4A-4D depict 6 FEWGs for illustrative purposes, but in other embodiments, there are fewer or more than 6 FEWGs. For example, in some embodiments, there are 1 to 10 FEWGs coupled to each microwave energy generator. In some embodiments, a power combiner can be used to combine microwave energy from more than one microwave generator, and then the combined microwave energy can be coupled into more than one FEWG. The microwave energy emitted from such a power combiner can be very large and can be coupled into many FEWGs (for example, more than 10). In some embodiments, multiplexing is used to couple microwave energy from a single microwave energy source into multiple FEWGs. In one example, the multiplexing system is time-sharing multiplexing, which means coupling energy from a microwave energy source to a group of FEWGs at one time, and using a switch to direct the energy to a different group of FEWGs at a later time. The switch can be used to cycle energy from a single microwave energy source between many groups of FEWG (for example, more than 2 groups, or more than 5 groups, or more than 10 groups) over time, where each group of FEWG may contain multiple FEWG ( For example, more than 2, or more than 5, or 1 to 10). Figures 4B and 4D depict two outlets, but there may be more than two outlets, and each FEWG may have its own outlet for collecting separated components. In some embodiments, there are 1 to 10 outlets for collecting separated components. Figures 4B and 4D depict 3 FEWGs connected to each outlet, but there may be fewer or more than 3 FEWGs connected to each outlet, and each FEWG may have its own for collecting separated components The exit. Figures 4C and 4D depict two microwave energy generators, but in some embodiments, there are more than two microwave energy generators. In some embodiments, there are 1 to 10 FEWG connected together into each outlet for collection of separated components.

5A to 5B show an embodiment of the microwave chemical processing system of the present disclosure, in which multiple FEWGs are coupled to a microwave energy generator (ie, a microwave energy source) using different geometric structures. The FEWG in these embodiments can share some or all of the features of the system described above. The supply gas and process material input in these embodiments can also share some or all of the features described above. In some embodiments, each FEWG has a reaction zone. In some embodiments, plasma is generated from the supply gas in the plasma zone in each of the FEWGs, and the reaction length of each of the FEWGs serves as a reaction zone to separate the process materials into individual components . In some embodiments, the reaction zones are connected together and the microwave chemical processing system has an outlet for separating components. In some embodiments, the reaction zones are connected together and the microwave chemical processing system has more than one outlet for separating components. In some embodiments, each reaction zone has its own outlet for separating components.

Figure 5A shows an embodiment with a manifold geometry in which there is a microwave energy generator coupled to multiple FEWGs. The microwave energy 501 is coupled to the manifold waveguide 502 and then into multiple FEWGs. The microwave energy enters the large cross-sectional area section of each FEWG, then enters the field enhancement zone of FEWG 503, and is then coupled to the smaller cross-sectional area reaction zone of FEWG 504. In the embodiment depicted in Figure 5A, all FEWGs are all connected together so that there is a single outlet 505 for collecting the separated components.

Figure 5B shows an embodiment with a mesh geometry in which there is a microwave energy generator coupled to multiple FEWGs. The microwave energy 501 is coupled to the mesh waveguide 502 and then into multiple FEWGs. The specific mesh waveguide size depends on the microwave frequency used. The microwave energy enters the large cross-sectional area section of each FEWG, then enters the field enhancement zone of FEWG 503, and is then coupled to the smaller cross-sectional area reaction zone of FEWG 504. In the embodiment depicted in Figure 5B, all FEWGs are all connected together so that there is a single outlet 505 for collecting the separated components.

Figures 5A to 5B depict a microwave energy generator coupled to 5 FEWGs in a manifold or mesh geometry, but in other embodiments, there are fewer or more couplings to a manifold or mesh geometry. One microwave energy generator in 5 FEWGs. In some embodiments, a power combiner can be used to combine microwave energy from more than one microwave generator, and then the combined microwave energy can be coupled into more than one FEWG in a manifold or mesh geometry. The microwave energy emitted from such a power combiner can be very large and can be coupled to many FEWGs (for example, more than 10) in a manifold or mesh geometry. In some embodiments, there are 1 to 10 FEWGs coupled to each microwave energy generator in a manifold or mesh geometry. Figures 5A to 5B depict one outlet, but there may be more than one outlet from the FEWG coupled to the microwave energy generator with a manifold or mesh geometry. In some embodiments, there are 1 to 10 outlets for collecting separated components from a FEWG coupled to a microwave energy generator in a manifold or mesh geometry. Figures 5A to 5B depict one microwave energy generator coupled to multiple FEWGs, but in some embodiments, there are 1 to 10 microwave energy generators coupled to 1 to 10 FEWGs in a manifold or mesh geometry . In some embodiments, there are 1 to 10 FEWGs connected together into each outlet for collecting separated components from the FEWG coupled to the microwave energy generator in a manifold or mesh geometry.

In some embodiments, there is a void between the manifold or mesh geometry waveguide 502 and the field enhancement region of the FEWG 503. The size of these apertures is tailored to efficiently couple the microwave energy from the manifold or mesh geometry waveguide 502 to the field enhancement zone of the FEWG 503. In some embodiments, the sizes of these apertures are different sizes to balance the transmission of microwave energy from the manifold or mesh geometry waveguide 502 between all the coupled field enhancement regions of the FEWG 503.

In some embodiments, the dimensions of the manifold or mesh geometry waveguide 502 are tailored so that it forms a resonant cavity and there is a standing wave of microwave energy within the manifold or mesh geometry waveguide 502. In some embodiments, the standing wave of microwave energy is tuned to effectively couple microwave energy into each of the coupled field enhancement regions of FEWG 503.

In some embodiments, there is a controlled leakage from the manifold or mesh geometry waveguide 502 to the field enhancement zone of the FEWG 503 to effectively distribute the amount of microwave energy coupled to each of the reaction zones of the FEWG 504 . Some design examples for controlling the leakage from the manifold or mesh geometry waveguide 502 to the field enhancement zone of FEWG 503 and effectively distributing the amount of microwave energy coupled to each of the reaction zones of FEWG 504 are: Change the cross section and/or length of the waveguide; use the aperture between the manifold or mesh geometry waveguide 502 and the field enhancement region of the FEWG 503; change the manifold or mesh geometry waveguide 502 and the field enhancement region of the FEWG 503 The orientation angle between the two; the use of filaments, point sources, electrodes, and/or magnets (discussed in more detail below) in the manifold or mesh geometry waveguide or in the FEWG; and two of these design features Or a combination of two or more. Additional features in microwave chemical processing reactors with field-enhanced waveguides

In addition to the above features of the microwave processing system with FEWG, further features that can be used in the system described above will now be discussed.

Fig. 6 shows a microwave process system with FEWG, in which plasma is generated in one or more precursor gases, and the precursor gas system is inserted upstream of the position where the process material flows into the reaction zone of the FEWG. The precursor gas improves the cracking efficiency by adding substances with various ionization potentials. That is, different gases have different ionization energies, and the ionization energy is the amount of energy required to remove electrons from atoms or molecules. In addition, various gases have different paired generation (how many electrons can be generated per ion) and secondary electron emission properties (emission of electrons when charged particles hit the surface). Therefore, in the present disclosure, the use of precursor gas can be used to influence the energy of the plasma.

In FIG. 6, similar to the previous embodiment, the microwave gas processing system 600 includes a microwave energy generator (ie, a microwave energy source) 604, a FEWG 605, and a microwave transmitter circuit 607. For the sake of clarity, the diagram in FIG. 6 is a simplified diagram compared with the previous diagrams. The supply gas inlet 602 receives a precursor gas 620 that supplements a supply gas (not shown) to generate plasma in the waveguide. In various embodiments, the precursor gas 620 may include one or more of hydrogen, argon, helium, or various inert gases. Similar to the previous embodiment, the process material inlet 610 is configured to receive the process material to be reacted.

In some embodiments, one or more of the separated components of the process material is recycled back into the supply gas and/or process material entering the FEWG 605. For the precursor gas that is not the required output product of the system (for example, the argon precursor gas in the methane treatment), the precursor gas is removed from the separated components 630 and 632 in the post-processing step. The separated components 630 and 632 are Output from exit 603. As shown in Figure 6, the gas reaction in FEWG 605 produces separated components 630 and 632. For example, for methane as a process material, the first separated component 630 can be carbon and the second separated component 632 can be H ₂ gas (which is ^{recombined from atomic hydrogen H+} and then collected at the outlet 603). Alternatively, the first separation component 630 can be CH ₂ and the second separation component 632 can be hydrogen H ₂ . The separated component 632 is recycled back into the FEWG 605 via the conduit 640 and back to the supply gas inlet 602. The recycled separated component 632 is therefore used as the precursor gas 620. Although it is counterintuitive to return the generated separated components to the reaction system, the recycling of the components adds energy to the plasma and, in some embodiments, can also contribute to the thermal cracking of the process materials, because the recirculation of the components adds energy to the plasma. The circulating components have been heated during the gas treatment. In some embodiments, for example, for processes where a total of 150-200 slm of H ₂ is produced, the separated component 632 may be 2-10 slm of H ₂ recycled back to the FEWG 605. As determined by a number of factors, such as the flow rate of the process material and/or the amount of energy desired to be added to the process to initiate the target chemical path, other amounts or parts of the separated components 632 can be recycled.

In some embodiments, some or all of the supply gas contains one or more separated components of the process material that are recycled. For example, the supply gas may be hydrogen, and the process material may be methane, the methane is reacted to form hydrogen and carbon, and at least a part of the hydrogen generated from the methane can be recycled and used as the supply gas. Recycling the generated hydrogen is beneficial to improve the overall gas processing efficiency, because the plasma formed from hydrogen is highly effective in cracking the hydrocarbon bonds in the molecules of the process material. In addition, in some embodiments, the recycled H ₂ is already at a high temperature, and therefore requires less energy input to achieve thermal cracking energy. In some embodiments, the supply gas is H ₂ provided by an external source, and recycled H ₂ is added to the external source. In these embodiments, the generated plasma is hydrogen plasma.

Figure 7 shows a microwave process system with FEWG and filaments. In the embodiment of FIG. 7, similar to the previous embodiment, the microwave processing system 700 includes a microwave energy generator (ie, a microwave energy source) 704, a FEWG 705, and a microwave transmitter circuit 707. The microwave energy 709 is supplied by the microwave energy source 704 to propagate in the direction along the length L of the FEWG 705. In this embodiment, the supply gas inlet 702 is placed _{near the inlet of the part L 0 instead of being placed at the inlet of the part L 1} (ie, the plasma region) as shown in the previous embodiment. One or more metal filaments 720 are placed in the FEWG 705 to assist the ignition of the plasma and/or the excitation of higher energy substances in the plasma. In this embodiment, the metal filament 720 is located downstream of the first gas inlet 702, near the inlet of the plasma region portion L ₁ of the FEWG (which has a smaller cross-sectional area compared to the FEWG that is closer to the microwave energy generator) . In other embodiments, the filament 720 may be located at other positions within _{the portion L 1 of the total length L of the FEWG 705, where L 1} is the region in the waveguide where the plasma is formed, as described in relation to the previous embodiment. In some embodiments, the filament 720 is located in the portion L ₁ of the FEWG and upstream of the process material inlet 710, so it will be located outside the portion L ₂ (ie, the length L ₂ shown in FIG. 3), where _The reaction in 2 is taking place and it can coat the filament with the reacted substance. The existence of the filament 720 can reduce the plasma ignition voltage by providing an ignition site and by concentrating the electric field of the microwave energy 709. In addition, the filament 720 may be heated and emit electrons through thermionic emission, thereby further helping to reduce the plasma ignition voltage. Although the filament 720 is shown as a single wire in this embodiment, the filament 720 may take other configurations, such as a coil or multiple filaments. In some embodiments, the filament 720 is tungsten. In some embodiments, the filaments may be actively energized (powered) or may be passive. In some embodiments, the filament 720 is an osmium filament adjacent to the heater coil (for example, assembled as a plate, or coil, or other shape). In some embodiments, the filament 720 is a ferrous material in the field of the induction coil. In some embodiments, the filament 720 is actively heated, wherein the active component (eg, the heating source component) is located outside the waveguide 705 and the filament material being heated is inside the waveguide 705.

Fig. 8 shows an embodiment of a microwave process system with FEWG and electron source. As in the previous embodiment, the microwave processing system 800 includes a supply gas inlet 802, a FEWG 805, and a microwave energy generator (ie, a microwave energy source) 804 for supplying microwave energy 809. The microwave processing system 800 also includes one or more electron sources 820 to assist in the ignition of the plasma and/or the excitation of higher energy substances in the plasma. The electron source 820 is configured to inject electrons into the FEWG 805, thereby reducing the amount of initial energy required to ignite the plasma. Therefore, the ignition level of the plasma can be controlled by controlling the amount of electrons present. In some embodiments, electrons are injected into the portion L ₁ of the total length L of the FEWG 805, where L ₁ is the region in the FEWG where the plasma is formed, as described above. For example, in this embodiment, the electron source 820 is configured to supply electrons into the FEWG 805 downstream of the first gas inlet 802. In some embodiments, the electron source 820 is a field emission source. In some embodiments, the electron source 820 contains an osmium element adjacent to the heater coil. In some embodiments, the electron source 820 contains ferrous materials in the field of the induction coil. In some embodiments, the electron source 820 contains filaments as described above, and a high-voltage electric field is used to inject the generated electrons into the portion L ₁ . In some embodiments, the electron source 820 is instead an ion source.

The advantage of using filament 720 and/or electron source 820 in FEWG is that it enables plasma to be formed quickly enough to keep up with the rapid microwave pulse frequency (for example, at a frequency greater than 500 Hz or greater than 1 kHz), This is true even in the case of high gas flow rates (for example, greater than 5 slm) and large gas volumes (for example, up to 1000 L). Under high pressure (for example, greater than 0.9 atm, or greater than 1 atm, or greater than 2 atm), this system is especially important because high-energy substances will quickly extinguish in high-pressure atmospheric pressure, and if the plasma cannot be ignited quickly enough, Under high pressure, there will be a low fraction of high-energy substances (that is, integrated over time) in the pulsed plasma.

FIG. 8 also shows an embodiment of the electrode 830 in the microwave processing system of the present invention with FEWG. The electrode 830 can be used independently of the precursor gas 620 in FIG. 6, the filament 720 in FIG. 7, or the electron source 820 in FIG. 8, or used in combination with the foregoing. In some embodiments, the system 800 contains one or more sets of electrodes 830 to add energy to the plasma. The electrodes are configured to generate an electric field in _{the portion L 1} of the total length L of the FEWG 805 _{, where L 1} is the region in the FEWG where plasma is formed, as described above. The electrode 830 is embodied in FIG. 8 as a pair of coplanar electrodes with opposite charges, the pair of coplanar electrodes being outside and on the opposite side of the part of the FEWG 805 where the plasma 806 is generated. The electrodes can be energized to a specific voltage to accelerate the charged materials in the plasma to a desired level, thereby controlling the plasma energy. The electrode of this embodiment can be used with continuous wave microwave energy, but it is particularly effective in combination with pulsed microwave input. In the conventional system with electrodes and continuous microwave energy, the plasma between the electrodes will be localized in equilibrium (for example, near the electrodes), and the electric field and the electrodes are shielded, thereby restricting the electrodes from adding energy to the plasma. ability. However, when the microwave is pulsed, the plasma will exist in an unbalanced state for a larger fraction of time, and the electric field of the shield electrode will be reduced for a smaller fraction of time.

In some embodiments, the microwave processing system of the present disclosure will include magnets (not shown) to confine the plasma in the reaction zone and reduce the ignition voltage used to generate the plasma. In some embodiments, the magnet is a permanent magnet or an electromagnet. The magnet can be positioned so that the plasma density distribution can be controlled. In some embodiments, the magnet will increase _{the plasma density in the portion L 1} , thereby improving the efficiency of separating process materials by the plasma.

In some embodiments, filaments, point sources, electrodes, and/or magnets are used to customize the local impedance within the FEWG. In some embodiments, filaments, point sources, electrodes, and/or magnets are used to increase the plasma density in the reaction zone of the FEWG.

As previously described, a microwave energy generator coupled to a FEWG containing a reaction zone with a combination of the following can realize a cost-effective, high-productivity chemical gas processing system with low energy input requirements: pulsed microwave energy, high gas Flow rate (for example, greater than 5 slm), large plasma volume (for example, up to 1000 L), high pressure (for example, greater than 0.1 atm or greater than 0.9 atm, or greater than 2 atm), used to assist at the beginning of each pulse A filament or electron source for plasma ignition, and/or an electrode for further adding energy to the plasma.

The gas processing system with the above characteristics is configured in this way so that plasma is generated and the process materials are separated into components within the FEWG itself, such as Figure 2, Figure 3, Figure 4A to Figure 4D, Figure 5A to Figure 5B, Examples are depicted in Figure 6, Figure 7, and Figure 8. In these systems, the microwave energy enters the system upstream of the reaction that produces the separated components, and therefore the separated components accumulate on the microwave entry window of the reactor and the problem of absorbing the microwave energy before the microwave energy can generate plasma is alleviated . In the embodiment described herein, the part of the FEWG where the separated components are generated serves as a reaction chamber, and the flow of supply gas and/or the flow of process materials passing through the reaction chamber is parallel to the propagation direction of microwave energy in the FEWG. The microwave energy enters the FEWG upstream of the portion of the FEWG that serves as the reaction chamber, and separate components are generated in the reaction chamber.

In some embodiments, gas recirculation, filaments, and electron sources can be used in a microwave gas processing system with FEWG that utilizes continuous wave (CW) microwave energy. In an embodiment using CW microwave energy, gas recirculation, filaments, and electron sources will still help improve the gas processing efficiency of the system, reduce the ignition voltage of the plasma, and control the density distribution of the plasma.

In some embodiments, the separated component may adhere to the wall of the FEWG downstream of the reaction that produces the separated component, despite the large volume of the reaction zone in the FEWG. Although this does not prevent the generation of plasma, it still represents a production loss and pollution source in the system. Therefore, in some embodiments, the gas flow and process materials of the supply gas can be designed to generate plasma near the deposition area to remove the separated products deposited on the waveguide wall (or, the reaction chamber wall). In some embodiments, additional inlets for supplying gas and/or process materials can be configured to direct the gas to the deposition area, thereby removing the separated products deposited on the waveguide wall (or reaction chamber wall). Microwave gas processing method

Fig. 9 is an exemplary flow chart 900 showing methods for microwave processing of gases that use chemical control in high-efficiency gas reactions using FEWG. In step 910, microwave energy is supplied through a FEWG having a length, wherein the microwave energy propagates in a direction along the FEWG. Microwave energy can be pulsed or continuous wave. In some embodiments, it will have less than 100 kW, or 1 kW to 100 kW, or 1 kW to 500 kW, or 1 kW to 1 MW, or 10 kW to 5 MW, or greater than 10 kW, or greater than 100 kW, Or microwave energy with a time average power greater than 500 kW, or greater than 1 MW, or greater than 2 MW is supplied to the FEWG. In some embodiments, the pressure within the FEWG is at least 0.1 atmospheres, such as 0.9 atm to 10 atm. In step 920, a supply gas is provided into the FEWG at a first position along the length of the FEWG, where most of the supply gas flows in the direction of microwave energy propagation. In step 930, plasma is generated in the supply gas in at least a portion of the length of the FEWG. At step 940, the process material is added to the FEWG at a second location downstream of the first location. In some embodiments, most of the process materials flow at a flow rate greater than 5 slm in the direction of microwave propagation.

Optionally, in step 950, the average energy of the plasma is controlled to convert the process materials into separated components. The average energy may be 0.8 eV to 20 eV, for example. In some embodiments, the pulse frequency is controlled, where the pulse frequency is greater than 500 Hz. For example, the pulse frequency of microwave energy can be 500 Hz to 1000 kHz. In some embodiments, in addition to or instead of pulse frequency, the duty cycle of pulsed microwave energy is controlled, wherein the duty cycle is less than 50%.

Please note that the steps in Figure 9 can be performed in a different order than shown. For example, the process gas 940 can be added at the same point as the process 920; that is, before the step of generating plasma in step 930. In another example, the plasma energy control in step 950 can be performed in combination with the plasma generation in step 930.

In some embodiments, the process material is methane, and the separated components include hydrogen and nanoparticulate carbon. For example, nanoparticulate carbon may include one or more forms of graphene, graphite, carbon nanoonion, fullerene, or nanotube.

In some embodiments, a precursor gas is added to the supply gas at the first location, the precursor gas including hydrogen or an inert gas. In some embodiments, the separated component comprises H ₂ , and at least a portion of the separated component H ₂ is recycled back to the first location. In these embodiments, the supply gas includes H ₂ , and the plasma includes hydrogen plasma.

In various embodiments, the method includes providing a metal filament in the FEWG that is used to reduce the ignition voltage used to generate the plasma. In various embodiments, the method includes providing a pair of electrodes to the system, where the electrodes are configured to add energy to the generated plasma in the FEWG. Instance

The concept of generating plasma and reaction zone in the waveguide is demonstrated on the test system shown in the simplified isometric view of Fig. 10A and the photograph of Fig. 10B. The system of FIGS. 10A and 10B includes microwave energy 1001 entering the waveguide 1002, and plasma is generated in the reaction chamber portion of the waveguide 1004 coupled to the waveguide 1002. The field enhancement portion of the waveguide in the demonstrated system includes a sudden change in cross-sectional area 1003 instead of the tapered change as described in the previous embodiment. The reaction zone portion of the waveguide in this example has a circular cross section as shown in the inner plan view of FIG. 10B. As shown in Figure 10B, the reaction zone of the waveguide 1004 also contains filaments 1006 to further enhance the field in the reaction zone. The filament in this example is made of tantalum, titanium or tungsten, and is used to concentrate the electric field of microwave energy, thereby increasing the plasma density in the reaction zone and assisting the reaction to separate the process materials into separate components.

In this example, the microwave power entering the waveguide 1002 is 1 kW to 1.5 kW. The supply gas in this example is hydrogen with various percentages of argon introduced into the waveguide 1002 at a flow rate of 0.1 slm to 1 slm, and the process gas is introduced into the waveguide 1002 at a flow rate of 0.1 slm to 2 slm Methane. The separated components in this example are particles of carbon allotropes and hydrogen, and are collected at the outlet 1005.

Although this specification has been described in detail with respect to specific embodiments of the present invention, it should be understood that those skilled in the art can easily think of alternatives, changes, and equivalents to these embodiments after gaining an understanding of the foregoing. Without departing from the scope of the present invention, those of ordinary skill can practice these and other modifications and changes of the present invention. In addition, those skilled in the art will understand that the foregoing description is merely illustrative, and is not intended to limit the present invention.

100, 300‧‧‧Microwave chemical processing system 101‧‧‧Reaction chamber 102,202,302,310,602,610,702,710,802‧‧‧Entrance 103,203,303,403,505,603, 1005‧‧‧Exit 104, 204, 304‧‧‧Microwave energy source 105, 1002, 1004‧‧‧ Waveguide 106‧‧‧Microwave plasma 107,607,707‧‧‧Microwave transmitter circuit 108‧‧‧Processing materials 109, 209, 309, 501, 709, 809, 1001‧‧‧Microwave energy 200‧‧‧Microwave chemical treatment reactor 201,301‧‧‧Reaction zone/Reaction zone part 205,305,402,503,504,605 , 705, 805‧‧‧FEWG206‧‧‧Microwave plasma/plasma 207, 307‧‧‧Microwave circuit 208a‧‧‧Supply gas and/or process material 208b‧‧‧Supply gas and/or process material stream 210, 211‧‧‧Pressure barrier 212‧‧‧Pressure jet port 306‧‧‧Microwave plasma 308a‧‧‧Supply gas 308b‧‧‧Supply gas stream 311a‧‧Processing material 311b‧‧‧Processing material stream 401‧‧‧ Microwave energy generator 502‧‧‧Manifold or mesh geometry waveguide 600‧‧‧Microwave gas processing system 604,704,804‧‧‧Microwave energy generator (ie, microwave energy source) 620‧‧‧Precursor gas 630、632‧‧‧Separation component 640‧‧‧Cathode 700,800‧‧‧Microwave processing system 720,1006‧‧‧Filament 806‧‧‧Plasma 820‧‧‧Electron source 830‧‧‧Electrode 900‧ ‧‧Exemplary flowchart 910, 920, 930, 940, 950‧‧‧Step 1003‧‧‧Sudden change of cross-sectional area L, L _A , L _B , L ₀ , L ₁ , L ₂ ‧‧‧Length

Figure 1A is a vertical cross-section of a conventional microwave chemical processing system.

Figures 1B to 1C show exemplary geometric structures and dimensions of the waveguide of the present disclosure.

Figure 2 is a simplified vertical cross-section of a microwave gas processing system according to some embodiments of the present disclosure.

Figure 3 is a simplified vertical cross-section of a microwave gas processing system according to a further embodiment of the present disclosure.

4A to 4D are block diagrams of a microwave chemical processing system with multiple field enhancement waveguides and multiple microwave energy sources according to an embodiment of the present disclosure.

5A to 5B are schematic diagrams of a microwave chemical processing system in which a plurality of field-enhancing waveguides are coupled to a microwave energy generator according to an embodiment of the present disclosure.

Figure 6 is a simplified vertical cross-section of a microwave gas processing system with precursor gas input according to an embodiment of the present disclosure.

Figure 7 is a simplified vertical cross-section of a microwave gas treatment system with filaments according to an embodiment of the present disclosure.

Figure 8 is a simplified vertical cross-section of a microwave gas processing system according to an embodiment of the present disclosure, in which electron sources and electrodes are depicted.

FIG. 9 is an exemplary flowchart of a method for microwave processing of gas according to an embodiment of the present disclosure.

10A to 10B show the test system used to demonstrate the concept of generating plasma and reaction zone in the waveguide.

200‧‧‧Microwave chemical treatment reactor

201‧‧‧Reaction zone/Reaction zone part

202‧‧‧Supply gas and/or process material inlet

203‧‧‧Exit

204‧‧‧Microwave energy source

205‧‧‧FEWG

206‧‧‧Microwave plasma/plasma

207‧‧‧Microwave circuit

208a‧‧‧Supply gas and/or process materials

208b‧‧‧Supply gas and/or process material flow

209‧‧‧Microwave energy

210、211‧‧‧Pressure barrier

212‧‧‧Pressure jet port

L, L _A , L _B , L ₀ , L ₁ , L ₂ ‧‧‧Length

Claims (16)

A reactor system includes: a microwave energy source configured to generate microwave energy; a field enhanced waveguide (FEWG) used as a reaction chamber and coupled to the microwave energy source, the FEWG includes: A first cross-sectional area and a second cross-sectional area, the second cross-sectional area is farther from the microwave energy source than the first cross-sectional area; a field enhancement zone, which is set between the first cross-sectional area and the first Between two cross-sectional areas and having a cross-sectional area decreasing along the length of the FEWG, the FEWG further includes: a supply gas inlet configured to receive a supply gas; and a reaction zone along the length of the FEWG The length is set downstream of the supply gas inlet and is configured to generate a plasma in response to the supply gas being excited by the microwave energy source; and a process inlet, which is located downstream from the supply gas inlet and is configured with A raw material is injected into the reaction zone; a pair of electrodes are located outside the opposite sides of the FEWG close to the reaction zone, the pair of electrodes are assembled to generate an electric field, and the plasma and the raw material pass through the electric field And a combination; and an outlet, which is configured to output a carbon structure produced by the combination of the plasma and the raw material. Such as the reactor system of claim 1, wherein the process entrance is located close to the plasma. The reactor system of claim 1, wherein the reaction zone has a pressure of at least about 0.1 atmosphere. The reactor system of claim 1, wherein the supply gas includes hydrogen, helium or an inert gas. The reactor system of claim 1, wherein the shape of the FEWG is defined by one or more walls. The reactor system of claim 1, wherein the process inlet is configured so that the raw material flows into the reaction zone at a flow rate greater than about 5 standard liters per minute (slm). Such as the reactor system of claim 1, wherein the raw material further comprises a gas, a liquid or a colloidal dispersion. Such as the reactor system of claim 1, wherein the pair of electrodes are configured to generate an electric field in the FEWG. The reactor system of claim 1, wherein the pair of electrodes at least partially surround the FEWG. The reactor system of claim 1, wherein the supply gas is at least partially consumed to generate the plasma. The reactor system of claim 1, wherein the microwave energy source is configured to adjust one or more of a pulse frequency, a pulse duty cycle, a pulse shape, or an output power level of the microwave energy. Such as the reactor system of claim 1, wherein the raw material further comprises any one or more of carbon particles, colloidal dispersion liquid or a plurality of solid particles. Such as the reactor system of claim 12, wherein the plurality of solid particles are mixed with any one or more of water, alkanes, alkenes, fast hydrocarbons, aromatic hydrocarbons, saturated hydrocarbons or unsaturated hydrocarbons in liquid form . Such as the reactor system of claim 1, wherein the raw material further includes a solid inorganic material coated in an organic material, a graphene coated silicon, a composite material with an organic or inorganic material interlayer, or a carbon layer encapsulating the silicon core Any one or more of the silicon cores. Such as the reactor system of claim 1, wherein the raw material further contains _{any one or more of sulfur, SiH 4} , trimethylaluminum, trimethylgallium, or glycidyl methacrylate. The reactor system of claim 1, wherein the plasma is configured to convert the raw material into separated components in the reaction zone.

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